1. Field of the Invention
The present invention relates generally to shields for shielding selected electronic components and electronic sub-assemblies mounted on a printed wiring board assembly from electromagnetic interference (EMI) and/or from radio frequency interference (RFI). More particularly, the present invention relates to shields which provide ready access to shielded components for servicing.
2. Description of the Invention Background
Conventional EMI/RFI shielding systems use a number of individual electrically conductive shields constructed as containers which have sidewalls merging with an integral upper surface. An open-ended lower surface of each container is positioned on a printed wiring board assembly to enclose an electronic component or sub-assembly which is to be shielded. The open-ended surface is fixedly attached to the wiring board assembly, usually by soldering. Each individual container is connected to ground potential either by connection to a ground bus designed to intercept the solder area covered by the open-ended container surface, or by providing a common ground connection to all shields subsequent to soldering the open-ended container surfaces to the wiring board assembly. Frequently, the entire wiring board assembly is protected by an outer shield or housing against environmental influences such as, for example, dust, moisture, or intense light.
When access is required to electronic components shielded by such conventional container-shaped shields, for example, for testing or servicing purposes, individual shields must be removed by breaking the soldered connection between the open-ended surfaces and the wiring board. This procedure is time-consuming and frequently results in damage to the wiring board. Efficient troubleshooting is hindered since a technician will feel compelled to make an "educated guess" as to which shield to remove first and damage to the wiring board may be severe so as to preclude re-use of the wiring board. Thus, while "integral-container shields" provide desired EMI/RFI shielding of electronic components mounted on a printed wiring board, such prior art shields pose significant disadvantages when access to shielded components or sub-assemblies is required.